<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>this底层原理</title>
</head>

<body>
    <script>
        var obj = {
            bar: 1,
            foo: function() {
                console.log(this);
            }
        }
        obj.foo();
        // foo 存的是一个地址
        var foo = obj.foo;
        foo();
    </script>
</body>

</html>